(1) We developed an instrument to measure atmospheric methane automatically using the He-Ne laser absorption technique. Since this instrument was found to be sensitive to variations in temperature, pressure and flow rate in the detector housing, we added devices to stabilize these variables. Adopting a calibration interval to be 1 minute, a precision of 50 ppbv has been attained. A time resolution of 1 minute is useful for platforms such as automobiles and airships. We made observations over the Tokyo metropolitan area using an airship and in the paddy fields using a car, to obtain the data for the emission sources of atmospheric methane.(2) We modified a carbon monoxide instrument based on gas chromatograph/mercury oxide deduction detector to adapt for airborne operation. An aircraft experiment was made over East Hokkaido in winter, to find carbon monoxide mixing ratio to be 150-170 ppbv, broadly constant from the ground to 5km altitude. The instrument was further improved to attain a precision of 5 ppbv with a time resolution of 110s. It was extensively employed in the campaign observations at Mt.Norikura, in the airship observation over Tokyo, and in the aircraft campaign in East Hokkaido.(3) Field observations for tropospheric ozone and its precursor gases were made at Mt.Norikura and over Tokyo aloft an airship using a newly developed carbon monoxide instrument together with instruments for a nitric oxide/total odd nitrogen, ozone, water vapor and other meteorological parameters. A significant variation was found in the concentrations of ozone, carbon monoxide, nitric oxide and total odd nitrogen between different air masses : In the Mt.Norikura observation the air mass changed from southern to northern one during the day of a typhoon and after its passage. In the Tokyo observation the airship experienced both polluted and relatively clean air masses in the metropolitan area and on its outskirts.